1. Field of the Invention
The present invention relates to a pressure operation control module of a coolant recovery device, and in particular to one that uses a pair of high-pressure side and low-pressure side electromagnetic valves and a control circuit to control the operation of high and low pressure of a coolant recovery device and the operation of a motor.
2. The Related Arts
Coolant recovery devices have been widely used to applications of retrieving and collecting used coolant from coolant-operating machines, such as air-conditioners and refrigerators. A conventional coolant recovery device generally comprises a high-pressure connection terminal and a lower-pressure connection terminal selectively connected to a coolant-recovery machine and a storage tank in order to retrieve the used coolant from the coolant-recovery machine and store it in the storage tank. The conventional coolant recovery device is provided with a single pressure switch to control the activation and deactivation of a motor-based power source arranged inside the coolant recovery device. Such a pressure switch is incapable of identifying the pressure level of the high-pressure connection terminal or the low-pressure connection terminal and is operated through setting made on the basis of the coolant pressure in controlling the activation and deactivation of the motor-based power source of the coolant recovery device. This prevents the timing of activation and deactivation of the coolant recovery device from suiting the need for high precision operations. Further, the high-pressure connection terminal and the low-pressure connection terminal of the conventional coolant recovery device must be operated manually for rotating switch valves to open or close the high-pressure connection terminal and the low-pressure connection terminal of the coolant recovery device. This would cause inconvenience of operation for an operator. Further, opening and closing the opening switches are manually operated by an operator who visually observe pressure gauge reading of the high-pressure connection terminal and the low-pressure connection terminal of the coolant recovery device and also relying on the experience thereof in order to control the opening and closing of the high-pressure connection terminal and the low-pressure connection terminal of the coolant recovery device, making it hard to control the sequence and timing of opening or closing in a precise manner and readily leading to a poor efficiency of coolant recovery. Further, residue of coolant may be accumulated in pipes and leakage of coolant may be present. These are issues of conventional coolant recovery devices to be addressed.
Further, a conventional coolant recovery device comprises a press-variable cylinder in which a motor drives a piston/connection rod assembly to reciprocally move in the pressure-variable cylinder. However, such a movement cannot be kept in a condition of moving in a linear manner along a central axis and would lead to wearing between a piston head of the piston/connection rod assembly and an inner surface of the pressure-variable cylinder, eventually making it not possible to maintain air tightness between the pressure-variable cylinder and the piston/connection rod assembly and thus resulting in leakage. To cope with such a problem, the output power of the motor must be increased in order to compensate the loss caused by leakage, leading to an increase of power consumption of the entire device. This is generally not economic. Further, the rating power of the driving motor C must be increased and this leads to an increase of installation cost of the coolant recovery device, making it also not economic.
Prior art documents are known in this field. For example, Taiwan Utility Model M380467 discloses an electronic measurement device for a coolant recovery machine, in which an electronic measurement device and a pressure sensor are used to control the activation and deactivation of the coolant recovery machine. Although the issue of imprecise timing of activation and deactivation of the above-described coolant recovery device involving a single pressure switch can be alleviated, the high-pressure connection terminal and low-pressure connection terminal (namely the input pipe 111 and the output pipe 112) of the coolant recovery machine of this prior art document are structured such that manual operation of rotating a switch (14) (as shown in FIG. 1 of the prior art document) is necessary for controlling the opening or closing of the high-pressure connection terminal and the low-pressure connection terminal. There is still the same problem that it is hard to control the sequence and timing of opening or closing of the high-pressure connection terminal and the low-pressure connection terminal of the conventional coolant recovery machine and eventually leading to poor operation efficiency of the coolant recovery machine and problems of residue and leakage of coolant accumulated in pipes.
In addition, US patent publication No. 2011/0120242 discloses a portable refrigerant recovery unit and U.S. Pat. No. 7,878,081 discloses a portable refrigerant recovery unit. Both disclose the typical coolant recovery devices as those conventional ones discussed above and also suffer the same drawbacks and problems of imprecise operation of activation and deactivation of the coolant recovery devices controlled by using a single pressure switch and also the drawbacks and problems of being hard to precisely control sequence and timing of opening or closing a high-pressure connection terminal and a low-pressure connection terminal of the coolant recovery device and thus poor operation efficiency of the coolant recovery device and residue and leakage of coolant accumulated in pipes.